The invention relates to a rotor of an asynchronous machine, an asynchronous machine with such a rotor, and a production method for producing such a rotor.
Due to their simple design, asynchronous machines with cage rotors form robust motors and are therefore suitable for numerous applications.
To generate a sufficient starting torque in such a machine, inter alia deep-bar rotors are used, but these have comparatively high radial slots containing rectangular or wedge-shaped rods. Due to the radial height of these slots, the teeth between two slots are embodied as relatively narrow in the region of the base. This results inter alia in the development of saturation effects in the rotor lamination that impair the operational performance of the machine.
To improve the energy efficiency of asynchronous machines, use is also made of copper hybrid motors, wherein, in the case of larger motors, in particular larger shaft heights, there is a problem that it is comparatively difficult to connect different conductive materials, such as, for example, copper rod and aluminum. This means the copper rods have to have a special geometric shape, but this makes the production of such a rotor more expensive.
Herein, the above-mentioned hybrid motors are provided with copper rods that can be introduced comparatively loosely into a slot provided for this purpose in the motor's rotor. Then, the electrical connections and fittings for the copper rods in the slot are produced by means of an aluminum diecasting method. Herein, the aluminum encloses the copper rod in the slot and on the outside, i.e. on the end faces of the rotor, forms the so-called end ring for connecting the rods to one another.
In the case of larger machines, in particular greater shaft heights, because of the difficulty in connecting copper and aluminum the copper rods must be inserted with a special coating.
Hence, herein the drawback is the complicated production method for asynchronous machines with cage rotors, in particular for efficiency classes of these asynchronous machines of above IE4.